Add ephemeral message support

bot/conn.go

@@ -14,6 +14,7 @@ type conn interface {
 	Connect(ctx context.Context) (<-chan event, error)
 	Send(channel *channelID, message string) error
 	SendWithID(channel *channelID, message string) (string, error)
+	SendEphemeral(channel *channelID, userID, message string) error
 	SendDM(userID string, message string) error
 	UploadFile(channel *channelID, message string, filename string, filetype string, file io.Reader) error
 	Update(channel *channelID, id string, message string) error

bot/conn_discord.go

@@ -79,6 +79,10 @@ func (c *discordConn) SendWithID(channel *channelID, message string) (string, er
 	return msg.ID, nil
 }
 
+func (c *discordConn) SendEphemeral(_ *channelID, userID, message string) error {
+	return c.SendDM(userID, message) // Discord does not support ephemeral messages outside of slash commands
+}
+
 func (c *discordConn) SendDM(userID string, message string) error {
 	ch, err := c.session.UserChannelCreate(userID)
 	if err != nil {

bot/conn_mem.go

@@ -67,6 +67,10 @@ func (c *memConn) SendWithID(channel *channelID, message string) (string, error)
 	return strconv.Itoa(c.currentID), nil
 }
 
+func (c *memConn) SendEphemeral(_ *channelID, userID, message string) error {
+	return c.SendDM(userID, message)
+}
+
 func (c *memConn) SendDM(userID string, message string) error {
 	c.mu.Lock()
 	defer c.mu.Unlock()

bot/conn_slack.go

@@ -81,6 +81,22 @@ func (c *slackConn) SendWithID(channel *channelID, message string) (string, erro
 	}
 }
 
+func (c *slackConn) SendEphemeral(channel *channelID, userID, message string) error {
+	options := c.postOptions(channel, slack.MsgOptionText(message, false))
+	for {
+		_, err := c.rtm.PostEphemeral(channel.Channel, userID, options...)
+		if err == nil {
+			return nil
+		}
+		if e, ok := err.(*slack.RateLimitedError); ok {
+			log.Printf("error: %s; sleeping before re-sending", err.Error())
+			time.Sleep(e.RetryAfter + additionalRateLimitDuration)
+			continue
+		}
+		return err
+	}
+}
+
 func (c *slackConn) SendDM(userID string, message string) error {
 	ch, _, _, err := c.rtm.OpenConversation(&slack.OpenConversationParameters{
 		ReturnIM: true,

bot/session.go

@@ -32,7 +32,7 @@ const (
 	sessionStartedMessage = "🚀 REPL session started, %s. Type `!help` to see a list of available commands, or `!exit` to forcefully " +
 		"exit the REPL."
 	splitModeThreadMessage            = "Use this thread to enter your commands. Your output will appear in the main channel."
-	onlyMeModeMessage                 = "Only you as the session owner can send commands. Use the `!allow` command to let other users control the session."
+	onlyMeModeMessage                 = "*Only you as the session owner* can send commands. Use the `!allow` command to let other users control the session."
 	everyoneModeMessage               = "*Everyone in this channel* can send commands. Use the `!deny` command specifically revoke access from users."
 	sessionExitedMessage              = "👋 REPL exited. See you later!"
 	sessionExitedWithRecordingMessage = "👋 REPL exited. You can find a recording of the session in the file below."
@@ -257,9 +257,6 @@ func (s *session) Run() error {
 	if err != nil {
 		return err
 	}
-	if err := s.maybeSendStartShareMessage(); err != nil {
-		return err
-	}
 	command := s.createCommand()
 	if err := s.tmux.Start(env, command...); err != nil {
 		log.Printf("[%s] Failed to start tmux: %s", s.conf.id, err.Error())
@@ -268,6 +265,9 @@ func (s *session) Run() error {
 	if err := s.conn.Send(s.conf.control, s.sessionStartedMessage()); err != nil {
 		return err
 	}
+	if err := s.maybeSendStartShareMessage(); err != nil {
+		return err
+	}
 	s.g.Go(s.userInputLoop)
 	s.g.Go(s.commandOutputLoop)
 	s.g.Go(s.activityMonitor)
@@ -701,7 +701,7 @@ func (s *session) maybeSendStartShareMessage() error {
 		return err
 	}
 	message := fmt.Sprintf(shareStartCommandMessage, port, s.conf.share.user, host)
-	if err := s.conn.SendDM(s.conf.user, message); err != nil {
+	if err := s.conn.SendEphemeral(s.conf.control, s.conf.user, message); err != nil {
 		return err
 	}
 	return nil